The present invention relates to method and apparatus for prefeeding corrugated boards to a box finishing machine. Although the present invention is particularly suitable for feeding corrugated boards, the present invention should be applicable to feeding other types of sheet material. Prefeeders, also called block feeders or load feeders, are well known in the corrugated box industry for feeding six foot tall stacks of sheets into the hopper of a finishing machine such as a flexo printer, a rotary die cutter, a platen die cutter, a printer slotter, or a flexo folder gluer. Prefeeders are generally made to handle a range of rectangular sheets where generally the short dimension of the sheets extends in the direction of flow and the long dimension is transverse to the direction of flow. Prefeeders are made this way because most finishing machines are also built to process rectangular sheets with the long dimension transverse to the direction of flow.
An inkjet printer, also known as a digital printer, for corrugated sheets prints along a path transverse to the direction of flow of the sheets. Such printers are sometimes called narrow path printers. A prefeeder for such a machine needs to feed rectangular sheets into the hopper in two modes. When the long dimension of the sheet is greater than the length of the print bath, the rectangular sheets need to be fed into the hopper with their long dimension in the direction of flow. However, if the long dimension of the rectangular sheets is less than the length of the print path, then the sheets should be fed into the hopper in the conventional manner with their long dimension transverse to the direction of flow. Other finishing machines, such as the narrow path flexo printer or rotary die cutter, may also need such a prefeeder.
There is a need in the corrugated box industry for methods and apparatus for feeding sheets into a narrow path printer or other box finishing devices which take advantage of the developed technology of conventional prefeeders which input six foot tall stacks of corrugated sheets in a box plant in the conventional manner of flow; that is, with the long dimension of the rectangular sheets in the stack transverse to the direction of flow. The present invention provides this need.